Here are some additional ideas to speed up the checking:
Make sure you have your own Client ID
Remove --tpslimit=10 (unless a test has shown that it is needed, if so then ignore the other ideas too)
Add --drive-pacer-min-sleep=10ms (to use the latest limits from Google)
Change --checkers=16 (to increase concurrency)
I don’t know how they will play with all the other parameters. I would perform some tests to find the 2-3 parameters that makes the most difference and then leave the rest at defaults (remember --dry-run).
I have assumed default settings for Google Drive in your config.